Microwave clothes dryers have heretofore been patented, as is apparent from those illustrated for example in U.S. Pat. No. 4,334,136 to Mahan et al, U.S. Pat. No. 4,356,640 to Jansson, U.S. Pat. No. 4,510,361 to Mahan, and U.S. Pat. No. 4,523,387 to Mahan. Such dryers generally comprise horizontal axis tumbler-type rotary drums in housings arranged to receive articles from which moisture is to be removed. The drums are rotatably supported, usually by cantilevered bearing supports, and the dryer housings include front doors through which articles are loaded into and unloaded from the drum. Microwave power means, such as magnetrons, are mounted in the housings, or in the doors, and have their outputs directed into the drum. Forced air is employed for removing moisture from the drums and, in many cases, to also cool the microwave power means. The microwave power means, in turn, heats the forced air before the latter's entry into the drum, to increase the vapor carrying capability of the forced air.
Although provisions have been made in prior art microwave clothes dryers for limiting microwave leakage from the housing through the doors or other openings or seams of the dryer, which provisions generally are similar to those that have been developed in connection with sealing the doors of microwave ovens with respect to their stationary housings, little thought has been given to the manner in which microwave leakage can be sealed at the interface between rotary and stationary parts of the dryers, such as between the cantilevered stationary bearing support for the drums and the rotating drums themselves.
This problem has heretofore been considered in connection with sealing the rotary interface of a fan on a microwave oven with the stationary housing of the oven, as shown in U.S. Pat. No. 4,303,817 to Klement et al. However, the Klement et al approach does not take into account the significant differences extant between driving arrangements employed in driving a blower fan and driving arrangements employed in driving a heavily loaded dryer drum.
The problem has also been considered, at least in part, in the aforementioned U.S. Pat. No. 4,523,387 to Mahan, wherein a zig-zag labrynthine leakage path is provided between a rotary drum and its stationary housing in an attempt to limit microwave energy leakage therebetween. However, this arrangement is devoid of any microwave chokes or traps and, thus, can only provide limited attenuation of such leakage energy at best. Moreover, in this case the drum is supported at multiple points about its periphery, rather than by a cantilevered bearing support, so that there is no cooperative relationship extant between the sealing arrangement and the drum support and driving arrangement.
It is, therefore, a primary object of the present invention to provide an improved microwave clothes dryer having an improved microwave leakage sealing arrangement between the rotating drum thereof and a bearing support for the drum.
Another object of the present invention is to provide an improved microwave leakage sealing arrangement for a mirowave clothes dryer in which the microwave leakage seal also serves as a drive pulley for rotating the drum of the dryer.
A further object of the invention is to provide an improved microwave clothes dryer in which the drive mechanism for the dryer drum includes a microwave choke that surrounds the stationary bearing support for the drum and cooperates therewith to attenuate the leakage ofmicrowave energy from the drum.
Additional objects and advantages of this invention will become apparent as the following description proceeds.